A K-band ruby maser with 500-MHz bandwidth

Engineering improvements to a previously described reflected-wave maser design have resulted in an instantaneous 3-dB bandwidth of 400 MHz at 19.5 GHz, increasing to 560 MHz at 24 GHz. Nominal gain is 27 to 31 dB and gain flatness is + or - 2.5 dB over this tuning range. Noise temperature variation across the passband is less than + or 1.5 K and the effective noise temperature referred to the room temperature input flange ranges from 9.5 + or - 4 K to 13.5 + or - 4 K over the 18.5- to 25-GHz tuning range.